Adaptive Friction Compensation for Bi-Directional, Low-Velocity
N.E. Leonard and P.S. Krishnaprasad
In Proceedings of the 31st IEEE Conference on Decision and
December, 1992, p. 267-273.
This paper presents a comparative
investigation of friction-compensating
control strategies designed to improve low-velocity position tracking
performance in the presence of velocity reversals
for servomechanisms. The methods considered
include adaptive control and estimation-based control. Additionally,
the various controller designs incorporate different friction models
ranging from classical friction and Stribeck friction to the less
popular Dahl friction model. This investigation of friction models
is motivated by the fact that there is little consensus in the
literature on how best to model friction for dynamic friction
The control strategies are compared in an extensive test program
sinusoidal position trajectory
tracking experiments on a direct-drive dc motor. We focus attention
on comparative experimental results of friction
compensation especially with repeated velocity reversals.
The results show that the adaptive and estimation-based
controllers outperform more traditional linear controllers.
The experiments also yield insight into the appropriateness of the
different friction models under the tested operating conditions.
particular, the Dahl model, typically ignored in the literature,
proves to be significant for the friction-compensating control problem
with repeated zero-velocity crossings. }
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